Process for the preparation of unsaturated aldehydes

ABSTRACT

A PROCESS FOR PREPARATION OF A,B-OLEFINICALLY UNSATURATED CARBONYL COMPOUNDS OF FORMULA   R(-C(-R8)=C(-R6)-CH(-R5)-C(-R3)(-R4)-C(-R2)=C(-R1)-CHO   BY CONDENSING, WITH A CONDENSING AGENT AT 60* TO 400* C., A BUTADIENYL ETHER (OR A SUBSTANCE WHICH GENERATES SUCH ETHER) OF FORMULA   R3-C(-R4)=C(-R2)-C(-R1)=CH-O-Y   WHEREIN Y IS A LINEAR OF BRANCHED C1-C4 ALKYL RADICAL, OR A BENZYL, P-NITROBENZYL OR FURFURYL RADICAL AND R1,R2, R3 AND R4 EACH IS HYDROGEN OR A LINEAR OR BRANCHED C1-C6 ALKYL RADICAL, WITH AN ALLYL ALCOHOL CONTAINING AT LEAST THREE CARBON ATOMS AND AT LEAST FOUR CARBON ATOMS LESS THAN THE END PRODUCT, OF FORMULA   R7-C(-R8)=C(-R6)-CH(-R5)-OH   WHEREIN R5,R6,R7 AND R8 EACH IS HYDROGEN, OR (A) A LINEAR OR BRANCHED C1-C8 ALKYL RADICAL, OR (B) A LINEAR OR BRANCHED C2-C8 OLEFINICALLY UNSATURATED HYDROCARBON RADICAL CONTAINING AT MOST TWO DOUBLE BONDS, OR (C) R5,R6 AND ONE OF R7 AND R8 EACH IS AS DEFINED IN (A) OR (B) ABOVE AND THE OTHER OF R7 AND R8 IS AN ETHYL RADICAL SUBSTITUTED ON ITS TERMINAL CARBON ATOM WITH: (1) AN UNSUBSTITUTED OR MONO- OR DI-METHYL-SUBSTITUTED C5 OR C6 OLEFINICALLY UNSATURATED CYCLOALIPHATIC GROUP CONTAINING AT MOST TWO DOUBLE BONDS ONE OF WHICH IS IN THE A-POSITION RELATIVE TO SAID TERMINAL CARBON ATOM, OR (2) AN UNSUBSTITUTED OR MONO- OR DI-METHYLSUBSTITUTED C7 OLEFINICALLY UNSATURATED BRIDGED CYCLOALIPHATIC GROUP CONTAINING A DOUBLE BOND IN THE A-POSITION RELATIVE TO SAID TERMINAL CARBON ATOM, OR (3) A 2- OR 3-FURYL OR A 2- OR 3-THIENYL GROUP, AND TWO OF THE ABOVE-DEFINED RADICALS R5,R6, R7 AND R8 MAY BE LINKED TO EACH OTHER (EXCEPT R5 TO R6) TO FORM: (4) A C5 OR C6 OLEFINICALLY UNSATURATED CYCLOALIPHATIC RING WHICH CONTAINS AT MOST TWO DOUBLE BONDS AND WHICH MAY BE SUBSTITUTED WITH C1-C3 ALKYL OR ALKENYL GROUPS, OR (5) A C6 OLEFINICALLY UNSATURATED BRIDGED CYCLOALIPHATIC RING WHICH CONTAINS ONE DOUBLE BOND AND WHICH MAY BE SUBSTITUTED WITH ONE OR TWO METHYL GROUPS, OR (6) A FURAN OR THIOPHENE RING WHICH MAY BE SUBSTITUTED WITH A METHYL GROUP. ALLYL ALCOHOLS AND UNSATURATED HYDROCARBONS ARE ALSO PREPARED BY REDUCING THE CARBONYL COMPOUNDS OBTAINED AS AFORESAID. COMPOUNDS OBTAINED IN THE FOREGOING THREE CATEGORIES HAVE VALUABLE ODORIFEROUS AND/ OR FLAVORING PROPERTIES AND ARE USEFUL IN THE MANUFACTURE OF PERFUMES, PERFUMED PRODUCTS, FOODSTUFFS AND BEVERAGES. IN MANY CASES, THE COMPOUNDS ARE ALSO USEFUL AS INTERMEDIATES FOR SYNTHESIZING OTHER ODORIFEROUS AND/OR FLAVORING COMPOUNDS.

" United States Patent Office 3,654,309 Patented Apr. 4, 1972 C]. C07d 63/12, /16; C07c 45/00 Int. U.S. Cl. 260-332.3 R 24 Claims ABSTRACT OF THE DISCLOSURE A process for preparation of u,fl-olefinically unsaturated carbonyl compounds of formula by condensing, with a condensing agent at 60 to 400 C., a butadienyl ether (or a substance which generates such ether) of formula 1". wherein Y is a linear or branched C C alkyl radical, or a benzyl, p-nitrobenzyl or furfuryl radical and R R R and R each is hydrogen or a linear or branched C -C alkyl radical, with an allylalcohol containing at least three carbon atoms and at least four carbon atoms less than the end product, of formula wherein R R R and R each is hydrogen, or

(a) a linear or branched C -C alkyl radical, or

(b) a linear or branched C -C olefinically unsaturated hydrocarbon radical containing at most two double bonds, or

(c) R R and one of R and R each is as defined in (a) or (b) above and the other of R and R is an ethyl radical substituted on its terminal carbon atom with:

(1) an unsubstituted or monoor di-methyl-substituted C or C olefinically unsaturated cycloaliphatic group containing at most two double bonds one of which is in the u-position relative to said terminal carbon atom, or

(2) an unsubstituted or monoor di-methylsubstituted C olefinically unsaturated bridged cycloaliphatic group containing a double bond in the u-position relative to said terminal carbon atom, or

(3) a 2- or 3-furyl or a 2- or 3-thienyl group,

and two of the above-defined radicals R R R and R may be linked to each other (except R to R to form: a

(4) a C or C olefinically unsaturated cyclo aliphatic ring which contains at most two double bonds and which may be substituted with C -C alkyl or alkenyl groups, or I (5) a C olefinically unsaturated bridged cycloaliphatic ring which contains one double bond and which may be substituted with one or two methyl groups, or (6) a furan or thiophene' ring which may be substituted with"a methyl"group.

Allyl alcohols and unsaturated hydrocarbons are also prepared by reducing the carbonyl compounds obtained as aforesaid.

Compounds obtained in the foregoing three categories have valuable odoriferous and/ or flavoring properties and are useful in the manufacture of perfumes, perfumed products, foodstuffs and beverages. In many cases, the compounds are also useful as intermediates for synthesizing other odoriferous and/or flavoring compounds.

The present invention relates to a new process for preparing unsaturated carbonyl compounds, many of which are new substances. Most of these carbonyl compounds have valuable odoriferous and/or flavouring properties and are, therefore, useful as ingredients in the manufacture of perfumes and perfumed products and/or as flavouring agents for foodstuffs and beverages. Many of the said carbonyl compounds are also useful as intermediates for synthesising other odoriferous and/0r flavouring compounds. The invention also comprises those of the said carbonyl compounds which are new.

Furthermore the invention relates to processes for preparing allyl alcohols and unsaturated hydrocarbons derived from the said carbonyl compounds and also comprises those of the allyl alcohols and hydrocarbons which are new. Most of these allyl alcohols and hydrocarbons also possess valuable organoleptic properties and are useful for the same purposes as the above mentioned unsaturated carbonyl compounds.

In an attempt to synthesise aldehydes of the following structural type by condensing certain allyl alcohols with butadienyl ethers according to known methods [cf. L. Claison, Chem. Ber. 45, 3157 1912)] it was found that the expected products could not be obtained but that instead carbonyl compounds of a totally different and unexpected structural type were formed. This discovery was the basis for the development of novel process for preparing unsaturated carbonyl compounds.

The present invention relates to a process for the preparation of olefinically nap-unsaturated carbonyl compounds which contain at least seven carbon atoms and as a building unit at least one group having the following carbon skeleton which comprises condensing, by heating in the presence of a condensing agent, either (i) a butadienyl ether of formula wherein Y represents a linear or branched alkyl radical containing from 1 to 4 carbon atoms, or a benzyl, p-nitrobenzyl or furfuryl radical, and each of the symbols R R R and R represents hydrogen or a linear or branched alkyl radical containing from 1 to 6 carbon atoms,

(ii) a substance capable of generating a butadienyl ether of Formula I under the condensation conditions,

with

(iii) an allyl alcohol which contains at least three carbon atoms and at least four carbon atoms less than the required end product and which corresponds to formula 1 Ra Ra I =C- H-OH Rs II wherein each of the symbols R R R and R represents hydrogen, or

(a) a linear or branched alkyl radical containing from 1 to 8 carbon atoms, or

(b) a linear or branched olefinically unsaturated hydrocarbon radical containing at most two double bonds and from 2 to 8 carbon atoms, or wherein (c) R R and R or R have the meaning defined sub (a) and (b) whereas either R or R represents a substituted ethyl radical carrying on the terminal carbon atoms as a substituent an unsubstituted or monoor di-methyl-substituted fiveor six-membered olefinically unsaturated cycloaliphatic group containing at most two double bonds one of which is in the a-position with respect to the said terminal carbon atom, or a substituted ethyl radical carrying on the terminal carbon atom as a substituent an unsubstituted or monoor di-methyl-substituted seven-members olefinically unsaturated bridged cycloaliphatic group containing a double bond in the u-position with respect to the said terminal carbon atom, or a substituted ethyl radical carrying on the terminal carbon atom as a substituent a 2- or 3-furyl, or 2- or 3-thienyl group, and wherein (d) two of the radicals represented by the symbols R R R7 and R can be linked to each other, except R to R to 01111 a fiveor sixmembered olefinically unsaturated cycloaliphatic ring which contains at most two double bonds and which can carry as substituents alkyl or alkenyl groups containing from 1 to 3 carbon atoms, or a six-membered olefinically unsaturated bridged cycloaliphatic ring which contains one double bond and which can carry one or two methyl groups, or a furan or thiophene ring which can carry a methyl group,

in order to form a carbonyl compound of formula wherein the symbols R to R have the meaning defined above.

In the above Formula I of the starting butadienyl ethers the alkyl radicals represented by R R R and R include, e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl and isohexyl. Preferred alkyl radicals are methyl and ethyl. A preferred class of butadienyl ethers includes, e.g., butadienyl ethers,

as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-

heptyl and n-octyl, or branched alkyl radicals such as isopropyl, isobutyl, isopentyl, isohexyl, isoheptyl, isooctyl, 2-methylbutyl, 2-methylpentyl, S-methylpentyl, 2-

ethylpentyl, 3-ethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,4-dimethylpentyl, 2,3,3-trin'1ethylpentyl,

2,4-dimethyl-3-ethylpentyl, 2-methylhexyl, 3-methylhexyl,

4-methylhexyl, 2,3-dimethylhe'xyl, 2,4-dimethylhexyl, 2,5-

dimethylhexyl, 3,4-dimethylhexyl, 3,5-dimethylhexyl,' 3-

ethylhexyl and 4-ethylhexyl. Preferred alkyl radicals are methyl and ethyl. p r

In Formula II R R R and R can also represent linear or branched olefinically unsaturated hydrocarbon radicals such as vinyl, allyl, 3-butenyl, 4-pen-tenyl, 5

hexenyl, 6-heptenyl, 7-octenyl, a

3-ethyl4-methyl-3-pentenyl,

2,3-dimethyl-3-pentenyl,

2,4-dimethyl-2,4-pentadienyl,

2,3,4-trimethyl-2,4-pentadienyl,

4methyl-3-methylene-4-pentenyl,

2,3-dimethyl-2,4-pentadienyl,

3,4-dimethyl-2,4-pentadienyl,

4-methyl-2,4-pentadienyl,

3-methyl-2-pentenyl,

2,4-dimethyl-2-pentenyl,

3,4-dimethyl-2-pentenyl,

Z-hexenyl,

4-hexenyl,

5-methyl-4-hexenyl,

S-ethyl-B-hexenyl,

4-ethyl-5-hexenyl,

2,4-dirnethyl-3-ethyl-3-pentenyl,

2,4-dimethyl-3-pentenyl,

3,4-dimethyl-2,4-pentadienyl,

2-methyl-3-methylene-4-pentenyl,

2,4-dimethyl-3-methylene-4-pentenyl,

2,4-dimethyl 2,4-pentadienyl,

2-methyl-2,4-pentadienyl,

Z-methyl-Z-pentenyl,

4-methyl-2-pentenyl,

2,3-dimethyl-2-pentenyl,

2-methy1-2-hexenyl,

2,4-hexadienyl,

3,4-dimethyl-3-hexenyl,

3,5-dimethyl-3-hexenyl,

3,6-dimethyl-3-hexenyl,

2,3-dimethyl-4-hexenyl and 2,5-dimethyl-4hexenyl.

A preferred group of unsaturated hydrocarbon radicals includes 3-methyl-3-pentenyl, 4 methyl 3 pentenyl, 3- methylene-4-pentenyl and 3-methyl-2,4-pentadienyl.

In the event that in Formula II R; or R represents a substituted ethyl radical, the substituent can be, e.g., a cyclopenten-l-yl, cyclohexen-l-yl, 3,3 dimethyl cyclohexen-l-yl, 3,3-dimethyl 1,5 cyclohexadienyl or 7,7-dimethyl-3-bicyclo[3.1.1]heptenyl group. A preferred class of substituent groups includes the 2- and 3-furyl and 3- thienyl groups. 1

Two of the radicals R R R and R can be linked to each other and form, together with their carrier carbon atoms, rings. If R and R are'linked to each other, the resulting ring can be a furan, thiophene or 7,7-dimethyl-3- bicyclo[3.l.1]heptene ring. If R and R are linked to each other, the resulting ring can be a 2-methyl-5-isopropyl-l-cyclohexene or Z-methyl-S -isopropeny1cycl0- hexene ring.

A preferred class of starting allyl alcoholsof Formula II includes 2-rnethyl-6-vinyl-2,6-heptadien-l-ol, 3,7-dimethyl-1,3,6-octatrien-8-ol, geraniol, nerol, crotyl alcohol, tiglic alcohol, 2,6-dimethyl-2,6-octadienol, furfuryl alcohol, thenyl alcohol, 3-methoXymethyl-furan, myrtenol, carveol, piperitol, 5-(3-furyl)-2-methyl-2-pentenol and 9- (3-furyl) -2,6-dimethyl 2,6-nonadienol (neotorreyol) As a compound capable of generating I under the conditions of'the condensation, a compound of formula wherein R R R R and Y have the same meaning as in Formula I, can be used. Y is preferably a methyl or ethyl radical. As an example 2-methyl-1,1,3-triethoxybutane can be mentioned.

The nature of the condensing agent used in the process of the invention is not critical, and most of the conventional condensing agents can be used. These include mineral acids such as dry hydrogen chloride, sulphuric acid and phosphoricacid, organic acids such as acetic acid, tartaric acid, oxalic acid, malonic acid, phenyl-acctic acid, trifiuor-acetic acid, and salts of the said acids with metals capable of forming metal-organic complexes such as magnesium, aluminium, chromium, manganese, silver, cadmium, mercury, iron, cobalt and palladium. Lewis acids such as boron trifluoride are also suitable condensing agent's. Furthermore, acidic salts such as sodium or ammonium dihydrogenphosphate and sodium bisulphate can be usedas condensing agents. Mixtures of at least two of the above mentioned condensing agents can also be used. Preferred condensing agents are mercuric acetate, phosphoric acid, ammonium dihydrogenphosphate and mixtures of phosphoric acid and ammonium dihydrogenphosphate.

The condensation can be carried out by heating the reactants at temperatures of 60 to 400 C. Heating at temperatures in the vicinity of 100 C. for several hours, e.g. 48 hours, is the preferred technique in many cases. In some instances it is, however, advantageous to heat the reactants at higher temperatures, e.g. at about 300 to 380 C., for a short period of a few seconds to a few minutes. It can also be advantageous to carry out the condensation in an inert atmosphere, e.g. under nitrogen or carbon dioxide.

Moreover, the condensation can be carried out in the presence of a high-boiling organic solvent such as polyethylene glycol ether, e.g. diglym or triglym, or a halogenated or nitrated aromatic hydrocarbon, e.g. p-dichlorobenzene or nitrotoluene. An excess of one of the starting butadienyl ethers or allyl alcohols can also serve as a solvent. F One of the essential advantages of the process according to the invention resides in the fact that the carbon chain of a given allyl alcohol of Formula II can be extended by one butadiene unit. This operation can be repeated in order to enlarge at will the molecule of a starting material. Indeed, the reduction of the carbonyl compound of Formula III with lithium aluminium hydride according to known processes yields easily the corresponding allyl alcohol which can again be used as a starting material in the process of the invention..Thrs method is particularly convenient for the addition of methylatedbutadiene units, i.e. isoprene units.

The progressive addition of isoprene units is not per se a new accomplis'hment; it takes place for example in the formation of rubber (natural or synthetic) by polymerisation of isoprene or derivatives thereof, according to known procedures. However, the products obtained thereby are mixtures of substances of various molecular weights which cannot be separated byusual means. n the other hand, the process according to the invention allows to add at will just one, or successively several butadiene units to a given allyl alcohol. I

The butadiene units added successively can be identical or different. After each extension step the product can be isolated and characterised.

'One specific method of carrying out the process of the invention, therefore, consists in repeating at least once the condensation of a compound of Formula I or its precursor (cf. Formulae IV, V and VI) with a compound of Formula II using as a starting allyl alcohol a compound resulting from the reduction of a carbonyl compound obtained by a preceding condensation in order to form a carbonyl compound of Formula III comprising at least two building units having the carbon skeleton As an example of this embodiment, tiglic alcohol is condensed with Z-methyI-butadienyl ethyl ether by heating between and in the presence of mercuric acetate and sodium acetate in order to obtain 2,6-dimethyl- 2,6-octadien-al. This compound is then reduced with lithium aluminum hydride to 2,6-dimethyl-2,6-octadien-ol which is again condensed according to the process of the invention with 2-methylbutadienyl ethyl ether by means of the same condensation agents to form 2,6,l0-trimethyl- 2,6,10-undecatrien-al which shows interesting organoleptic properties and is useful in the perfume and flavour industries. Furthermore, this aldehyde can be reduced again to the corresponding allyl alcohol. This sequence can be represented as follows:

H3 CH3 The above sequence can be continued as desired in order to form carbon chains of higher and higher molecular weight.

The invention also relates to a process for the prepara tion of allyl alcohols which contain at least seven carbon atoms and as a building unit at least one group having the following carbon skeleton ar a which comprises either reducing the carbonyl function of a carbonyl compound obtained by condensation of a compound of Formula I or its precursor (Formulae IV, V and VI) with a compound of Formula II, or by reducing the hydroxyl function of an allyl alcohol obtained according to the process defined above. The reduction of the carbonyl group can be carried out by means of hydrazine or a derivative thereof, eJg. tosylhydrazine, in the presence of a strong alkali such as sodium or potassium hydroxide according to known methods (cf. Tetrahydron 19, 1127 (1963)). The reduction of the hydroxyl function of an allyl alcohol can be brought about by treating its tosylate with sodium amalgam, lithium aluminum hydride or sodium iodide in acetic acid according to known methods (cf. Fieser & Fieser, Advanced Organic Chemistry, Reinhold Publ. Corp., New York (1961)). As an example of using the processes of the invention, 3-hydroxymethylfuran is condensed with 2-methylbutadienyl ethyl ether in order to obtain, after heating at a temperature comprised between 350 and 400, 2-methyl- 5-(3-furyl)-2-penten-al which smells pleasantly and which can be used in the perfume industry. The corresponding allyl alcohol obtained by reduction with lithium aluminum hydride can be further reduced via its tosylate by known methods, for example with lithium aluminum hydride, to an odoriferous hydrocarbon, perillene, which is a constituent of the oil of Perilla citriodoral (cf. for example: Guenther, The Essential Oils, p. 700) which is used in the perfume industry.

2-methyl-5-(3-furyl)-2-penten-ol, if condensed again according to the process of the invention with 2-methylbutadienyl ethyl ether, yields torreyal having a citrus-like odour, of formula which, when reduced by the conventional methods already mentioned above, gives the corresponding alcohol, neotorreyol. These two substances are constituents of the oil of Torreya nucifera and are of interest to the flavour industry. The complete reduction of the oxygen function of these substances for example via the tosylhydrazone of torreyal according to known methods, or via the tosylate of neotorreyol, yields dendrolasin, an odoriferous product also contained in the oil of Torreya nucifera and in the body of certain ants (cf. for example Science 149, 1337 (1965) The process according to the invention is also useful for preparing a-sinensal and B-sinensal which are sesquiterpene aldehydes of formulae y CH0 CHO a-Sinensal (II), ,B-sinensal and their conformers had hitherto not been prepared synthetically. With the process according to the invention it is now possible to synthesize them by condensing 2-methylbutadienyl ethyl ether with, respectively, ocimenol' f (3,7-dimethyl-1,3,6-octadien-8-o1) or myrcenol (2-methyl-6-vinyl-2,S-heptadien-l-ol) which can be obtained'for example by SeO oxidation of ocimene and myrcene, respectively.

In the following examples, certain conventional techniques are performed as described below:

(A) COLUMN CHROMATOGRAPHY In a column having a diameter to length ratio of about A filled with silica (Merck, 0.008 mm.), the mixture to be separated is charged in a weight proportion equal to or'lower than of the weight of silica. The chromatogram is developed with benzene and the elution is carried out with benzene-chloroform solutions containing increasin; amounts of chloroform.

CHO

8 (B) VAPOUR PHASE CHROMATOGRAPHY,

This is performed on a 4 m. Carbowax column, at temperatures from 100 to 250 C. with a helium stream.

(C) REDUCTION .OF THE CARBONYL TO THE ALCOHOL FUNCTION Example l-Preparation of a and B-sinensal 1 A mixture of 10 g. of Z-methyl-6-vinyl-2,6-heptadien-1- 01, 25 g. of methylbutadienyl ethyl ether, 6.6 g. of mercuric acetate and 2.7 g. of powdered sodium acetate is heated for 1 8 hours at 98 under nitrogen protection. After cooling, the solid materials arefiltered and the liquid phase is neutralised by stirring with anhydrous potassium carbonate. Then distillation is effected in a high vacuum, and the fraction distilling over at 0.00 1 torr is collected. This fraction comprises [St-sinensal whose purity is higher than according to gas-chromatographic analysis (yield 43%). In the NMR the methyl group present in the portion of the field with the highest intensity has a resonance at 6:1.60 p.p.m. (corrected value). The mass and IR spectra are in agreement with those of natural ;5' 'sinensal (cf. J. Org. Chem. 30, 1690 (1965)), and the dinitrophenylhydrazone of synthetic B-sinensal (M.P. SO 81) does not show any depression of the M.P. in admixture with the dinitrophenylhydrazone of natural S-sinensal.

When using the same method and thejsame amounts of reactants but replacing the above vinylheptadienolby its isomer, 3,7-dimethyl-1,3,6-octatrien-8-ol, a-sinensal is obtained in a comparable yield, its dinitrophenylhydrazone melting at 96-98". The aand fi-sinensalspreparedac' cording to the above example have valuable fiavouring properties and are useful in the flavour industry.

\ Example 2.Preparation of transand cis-2,7,11-trimethyl-2,6,IO-dOdecatrien-l-al A mixture of 10 g. of geraniol, 25 g. of methylbutadienyl ethyl ether, 6.6 g. of mercuric acetate and 2.7 g. of sodium acetate is heated for 18 hours at 98 under nitrogen protection. After cooling, the liquid phase is neutralised and separated as indicated in Example 1, then distilled in a high vacuum. 9.3 g. of distillate are obtained which is purified by chromatography on a silica column. The analytical sample of 2,7,11-trimethyl-trans-cis-2,6,lO-dodecatrien-l-al thus obtained is again redistilled and converted into its dinitrophenylhydrazone, M.P. 83-84.

Analysis.-Calculated for C H O N (percent): C, 62.98; H, 7.05; N, 14.0. Pound (percent) C, 62.47; H, 7.29;-N, 14.5.

When replacing in theabove mixture geraniol by nerol and proceeding exactly under the same conditions, 11.5 g. of crude 2,7,11-trimethyl-trans-trans-2,6,10-dodecatrien-1- al are obtained, the dinitrophenylhydrazone of which melts at 102-104".

Analysis.-Calculated for C H O N (percent): C, 62.98; H, 7.05; N, 14.0. Found (percent): C, 63.6; H, 7.23; N, 14.8.

The aldehydes prepared according to the above example have valuable odoriferous and flavouring properties and are useful in the perfume and flavour industry.

Example 3.Preparation of 2-methyl-2,6-octadien-l al A mixture of crotyl alcohol (20 g.), 2-methylbutadienyl ethyl ether (50 g.), mercuric acetate (6.6 g.) and sodium The nomenclature is that adopted receutl h I a was used in place of B and'vice verse y t e pasty acetate (2.7 g.) is'heated for 17 hours at 100 under nitrogen. After cooling, anhydrous potassium carbonate g.) is added, the mixture is vigorously stirredand filtered. The filtrate is distilled and filtered. The filtrate is distilled and the fraction distilling over at 78-80/ torr is collectedpThere is thus obtained a yield of 40% of 2- methyl-2,6-octadien-1- al which is practically pure according to gas chromatography. The following derivatives are readily prepared by means of the usual methods: dinitrophenylhydrazone, M.P. 139-140, semicarbazone, M.P. 153-455. I

' The aldehyde prepared according to the above example have valuable odoriferous and flavouring properties and is useful in the perfume and flavour industry.

Example 4.Preparation of 2,6-dimethyl-2,6-octadiena1 6 p.p.m.

Isomer A Isomer B Aldehyde proton 10.01 9. 2s Methylene protons C-4- 2. 65 2. 32 Methyl protons O-2 1. 73 1. 70 Methyl protons C-6 1. 61 1. 61

Elemental analysis of isomer B and of two of its derivatives, the semicarbazone and the 2,4-dinitrophenylhydrozone, gives the following results:

Calculated for C H O (percent): C, 78.89; H, 10.59. Found (B) (percent): C,78.98; H, 10.66.

Calculated for C H N O (percent): C, 63.12; H, 9.15; N, 20.08. Found for the semicarbazone (percent): 63.27; H, 9.36;N, 19.97 (M.P. 175-6).

Calculated for C H N O (percent): N, 16.86. Found for the 2,4-dinitrophenylhydrazone (percent): N, 16.87.

The aldehydes prepared according to the above example'have valuable odoriferous and flavouring properties and are useful in the perfume and flavour industry.

By reduction of the mixture of isomers A and B with lithium aluminium hydride there is obtained in a nearly quantitative yield a mixture of the corresponding alcohols (A' and B) in proportions equivalent to those of the mixture of A and B. B.P. 105110/ 100 torr. NMR spectrum:

6 p.p.m.

Isomer A Isomer B (cis-trans) (trans-trans) 43112011 3.98 3. 84 Methyl C-Z 1. 73 1. 60 Methyl C-G. 1. 59 1. 59 Methyl (terminal) 1. 54 1. 54

3 The above. alcohols are useful intermediates for the synthesis of compounds useful in the perfume and flavour industry.

Example 5.Preparation of 2,6,10-trimethyl-2,6,l0-

dodecatrienal (m./e.): molecular peak 220; other fragments: 41 (100), 67 (100), 55 81 (85), 93 (70), 137 (60). '1 When in the above example isomer l-A' is replaced by isomer l-B (Example 4), there are obtained 1.7 g. of a product'which is identical with that obtained from 1-A' according to gas-chromatographic analysis.

The above product was-valuable odoriferous and flavouring properties and is useful in the perfume and flavour industry.

Example 6.Preparation of 2-methyl-5-(2-furyl)-2- I pentenal A mixture of 20 g. of furfuryl alcohol, 50 g. of Z-methylbutadienyl ethyl ether, 6.6 g. of mercuric acetate and 2.7 g. of anhydrous sodium acetate is heated for 18 hours at 100. After filtration and distillation (B.P. 48-49/ 0.05 torr) there are isolated 21 g. of a product which, by gas-chromatographic analysis, is shown to be 2-methyl-5- (2-furyl)-2-pentenal of 85% purity. It is purified by chromatography on silica. The double bond has trans configuration (about 95%). NMR spectrum: H (aldehyde) at 6:928 p.p.m.; methyl group at 6:1.69 p.p.m.; H (vinyl) at 6:6.39 p.p.m.

The elemental analyses of the product as well as of two of its derivatives are as follows:

Calculated for C H O (percent): C, 73.14; H, 7.37. Found (percent): C, 73.14; H, 7.47.

Calculated for C H N O (percent): C, 59.71; H, 6.83; N, 18.99. Found for the semicarbazone (percent): C, 59.84; H, 7.00; N, 18.70.

Calculated for C H N O (percent): C, 55.81; H, 4.68; N, 16.27. Found for the 2,4-dinitrophenylhydrazone (percent): C, 56.10; H, 5.29; N, 15.70.

The above product has valuable oderiferous and flavouring properties and is useful in the perfume and flavour industry.

3.4 g. of the aldehyde obtained above are reduced with lithium aluminium hydride. There are thus obtained 2.3 g. of 2-methyl-5-(2-furyl)-2-pentenol, B.P. 66/ 0.02 torr. The NMR spectrum shows the C1 methylene protons at 6:3.85 p.p.m. and the C-2 methyl protons at 6:1.56 p.p.m.

The above alcohol is a useful intermediate for the synthesis of compounds useful in the perfume and flavour industry.

Example 7.-Preparation of 2-methyl-5-(2-furyl)- l-pentene A solution of 2.5 g. of 2-methy1-5-(2-furyl)-2-pentenal prepared according to Example 6 and 3 g. of hydrazine hydrate in 50 ml. of ethylene glycol is refluxed for 30 min. Thereafter, a concentrated aqueous potassium hydroxide solution prepared from 12 g. of KOH is added and the mixture is slowly distilled for 1 hour. The distillate is extracted with pentane and the extract distilled, B.P. 37/ 0.03 from According to the NMR analysis the methyl group of the product is observed at 6:170 p.p.m. and the vinyl protons at 8:4.70 p.p.m.

Analysis.Calculated for C H O (percent): C, 79.95; H, 9.39. Found (percent): C, 80.70; H, 9.48.

The above hydrocarbon has valuable odoriferous and flavouring properties and is useful in the perfume and flavour industry.

Example 8.Preparation of 2-methyl-5-(3-furyl)- Z-pentenal A mixture of 10 g. of 3-hydroxymethylfuran, 25 g. of Z-methylbutadienyl ethyl ether, 3.3 g. of mercuric acetate and 1.4 g. of sodium acetate is heated for 20 hours at After filtration there are obtained by distillation 14.2 g. of a liquid, B.P. /l0 torr, which is then heated at elevated temperature for a short period. This can be achieved by introducing the liquid into a pyrolysis apparatus heated to 350-400 and simultaneously distilling the resulting product. However, higher yields are obtained by subjecting the liquid to ,a preparative vapour phase chromatography under usual conditions (150-200), the injection chamber (evaporator) being maintained at 350- 380. 2-methyl-5-(3-furyl)-2-pentenal (85% trans, 15% cis) is thus collected in 70% yield. NMR of the aldehyde protons: 6:9.28 p.p.m. (trans) and 6:9.38 p.p.m. (cis).

Analysis.-Calculated for C H O (percent): C, 73.14; H, 7.37. Found (percent): C, 72.88; H, 7.42.

-The above aldehyde has valuable odoriferous and flavouring properties and is useful in the perfume and flavour industry.

Example 9.-Preparation of 2,7,11-trimethyl-transcis-2,6,10-dodecatrienal A mixture of 10 g. of geraniol, 25 g. of 2-metyl-1,l,3-

triethoxybutane and 0.3 g. of 84% phosphoric acid is heated for 2 hours at 130460, while collecting the resulting alcohol vapours in a down-directed condenser. After cooling one neutralises with anhydrous K CO filters and distills. There are collected 6.2 g. of a liquid (B.P. l110/0.01 torr) which, after chromatography on SiO yields 1 g. of 2,7,11-trimethyl-trans-cis-2,6,l0- dodecatrienal whose dinitrophenylhydrazone melts at 83- 84.

Analysis-Calculated for C H O N (percent): C, 62.98; H, 7.05; N, 14.0. Found for the dinitrophenylhydrazone (percent): C, 62.47; H, 7.29; N, 14.5.

The above aldehyde has valuable odoriferous and flavouring properties and is useful in the perfume and flavour industry.

By reduction of 2,7,1l-trimethyl-trans-cis-Z,6,10-dodecatrienal with lithium aluminum hydride there is obtained the corresponding alcohol in a nearly quantitative yield.

The above alcohol is a useful intermediate for the synthesis of compounds useful in the perfume and flavour industry.

Example 10.-Preparation of 2,7,11-trimethyl-transcis-2,6,10-dodecatrienal A mixture of 20 g. of geraniol, 100 g. of 1,1,3-triethoxy- Z-methylbutane, 5 g. of amonium dihydrogen phosphate and 5 g. of mercuric acetate is heated under the same conditions as in Example 9. The cooled solution is neutralised with anhydrous K CO and then distilled in a vacuum of 0.001 torr. The distillate is chromatographed on SiO and gives 8.5 g. of pure 2,7,1l-trimethyl-trans-cis-2,6,10-dodecatrienal, identical with the product obtained in Example 9.

The above aldehyde has valuable odoriferous and flavouring properties and is useful in the perfume and flavour industry.

Example 11.Preparation of 2,7,l1-trimethyltrans-trans-2,6,IO-dodecatrienal A mixture of 100 g. of nerol, g. of mercuric acetate, 10 g. of ammonium dihydrogen phosphate and 500 g. of Z-methyl-l,1,3-triethoxybutane is heated for 3 /2 hours under the same conditions as in Example 9. By neutralisation with anhydrous K CO filtration and distillation in a vacuum of 0.001 torr there are obtained 102 g. of a liquid which is fractionated by means of a spinning-band column There are obtained 43.2 g. of pure 2,7,ll-trimethyl-trans-trans 2,6,10-dodecatrienal B.P. 87-89/0.001 torr.

The above aldehyde has valuable odoriferous and fiavouring properties and is useful in the perfume and flavour industry.

Example 12.Preparation of 2-methyl-4-(2- thenyl) -2-butenal A mixture of 10 g. of 2-hydroxymethylthiophene, g. of 2-rnethylbutadienyl ethyl ether, 3.3 g. of mercuric acetate and 1.75 g. of sodium acetate is heated for 18 hours at 100. After diltration and distillation there are obtained 12 g. of distillate which is chromatographed on silica. Di-(Z-thenyl) ether is isolated and then 2- methyl-4-(2-thenyl)-2 butenal. NMR spectrum: 6:1.69

12 ppm, 3H (methyl); 3.2 p.p.m., 4H (-CH 6.39 p.p.m., 1H, t broad'(H,.viny1); 9.27 ppm, 3H (heterocyclic H). v v

Analysis.Calcula ted for .C H OS' (percent):, C,

66.65; H, 6.71. Found (percent) C, 66.76; H, 6.96.

The above aldehyde has valuable flavourin'g properties and is useful in the flavour industry. I Example" 13.Preparation of 5-(2-furyl)-2-pentenal 6 p.p.m.

" A p B H aldehyde 9.38 9.41. H vinyl about 6, 2H--- 6.70, 1H, q, J=7 cps. MethyL. 2.1 3H. Methyl 1.93, 3H, d, J=7 cps.

CHz- 2.4-3.0, 4H-

The aldehyde B has valuable odoriferous and flavouring properties and is useful in the perfume and flavour industry.

Example 14.Preparation of 9-(3-furyl)-2,6-

dimethyl-2,6-nonadienal (torreyal) 11.2 g. of 5-(3-furyl)-2 methyl-2pentenal prepared according to Example 8 'are reduced with 1.5 g, of lithium aluminum hydride in dry ether to obtain 5-(3- furyl)-2-methyl-2-pentenol. This alcohol (6.5 g.) .is heated with 20 g. of 2-methylbutadienyl ethyl ether, 3.3 g. of mercuric acetate and 1.7g. of sodium acetate for-18 hours at 100. By usual treatment there are obtained 7.4 g. of a mixture, B.P. 1l1 at 0.001 torr, The crude torreyal thus obtained is purified by chromatography on 50 g. of silica. After a trace of impurity eluted by ml. of benzene, pure torreyal is eluted by a henzene-ether mixture (9:1). Microdistillation shows a B.P. 9395/0.001 torr.

Analysis.-Calculated for C H O (percent): C, 77.5; H, 8.68. Found (percent): C, 77.38; H, 8.88.

The NMR spectrum is identical with the spectrum of natural torreyal isolated from Torreya nuciferw (Bull. Chem. Soc. Japan 38, 381 (1965)) with the exception of an additional peak at. 6:9.97 p.p.m.- due to the presence of the cis-aldehyde (about 15% of the total). The mass and IR spectra are identical with thoseof the natural product. This product has valuable flavouring properties and is useful in the flavour industry.

Example 15.--Preparation of 9-(3-furyl)-2,6-dimethyl-2,6-nonadienol (neotorreyol) Example 16.-Preparation of fl-(4,8-dimethyl- 3,7- nonadienyD-furan (dendrolasin) 0.35 g. of neotorreyol is dissolved in 5 ml. of absolute ether and 0.285 g. of p-toluenesulfonyl chloride is added.

During 3 hours at 0, 0.17 g. of dry powdered KOH are added with constant agitating. The agitation is continued for a, further 3 hours during which time the mixture cools down to room temperature. After filtration and concentration at room temperature, 25 ml. of tetrahydrofuranare added and then, at 0.2 g. of lithium aluminum hydride. After allowing the mixture to come to room temperature again, the excess hydride is decomposed with water and .the mixture filtered and concentrated. The crude dendrolasin is purified by vapour phase chromatographyat 200. It possesses the same properties, retention time, NMR, IR and mass spectra as the natural product.

Analysis.Calculated for C H O (percent): C, 82.51; H, 10.16. Found (percent): C, 82.68; H, 10.01. Dendrolasin has valuable odoriferous and flavoring properties and is useful in the perfume and fiavouring industry.

Example 17. Preparati0n of 2-methyl-4-(8-a-pinenyD- Z-butenal g. of primary myrtenol, 25 g. of Z-methylbutadienyl ethyl ether, 3.3 g. of mercuric acetate and 1.75 g. of sodium acetate are heated for 36 hours at 100 under nitrogen. After cooling, the mixture is filtered and distilled.

' A mixture of 30 g. of cis-carveol, 75 g. of 2-methyl butadienyl ethyl ether, 9.9 g. of mercuric acetate and 5.25 g. of sodium acetate are heated 20 hours at 100' in a nitrogen atmosphere. The product is filtered, distilled and then heated at elevated temperature for a short period. This can be achieved by following the technique described in Example 8. The product obtained thereby consists of two fractions collectable at the output of the vapour phase chromatography column: These fractions, identified as the isomer cis and trans of 2-methyl-4 (1-methyl-4isopropenyl-1-cyclohexen-6-yl)-2 butenal, have valuable odoriferous properties and are useful in the perfume industry. NMR spectrum: 6:10.03 p.p.m. (cis-aldehyde);

=9.30 p.p.m. (trans-aldehyde).

-I claim:

1. A process for the preparation of olefinically a,,B-unsaturated carbonyl compounds which contain at least seven carbon atoms and as a building unit at least one group having the following carbon skeleton tea which comprises condensing, by heating at a temperature from about 60 to 400 C. in the presence of a condensing agent, efltective for condensing (i) or (ii) with (iii) as hereinafter defined either (i) a butadienyl ether of formula wherein Y represents a linear or branched alkyl radical containing from 1 to 4 carbon atoms, or a benzyl, p-nitrobenzyl or furfuryl radical, and each of the symbols R R R and R represents hydrogen or a linear or branched alkyl radical containing from 1 to '6 carbon atoms,

14 (ii) a substance capable of generating a butadienyl ether of Formula Iunder the condensation conditions,

'(iii) an allyl alcohol which contains at least three carbon atoms and at least four carbon atoms less than the required end product and which corresponds to'forwherein each of the symbols R R R7 and R re presents hydrogen, or

(a) a linear or branched alkyl radical containing from 1 to 8 carbon atoms, or

(b) a linear or branched olefinically unsaturated hydrocarbon radical containing at most two double bonds and from 2 to 8 carbon atoms, or wherein (c) R R and R or R have the meaning defined sub (a) and (b) whereas either R or R represents a substituted ethyl radical carrying on the terminal carbon atom as a substituent an unsubstituted or monoor di-methyl-substituted fiveor six-membered olefinically unsaturated cycloaliphatic group containing at most two double bonds one of which is in the a-position with respect to the said terminal carbon atom, 'or a substituted ethyl radical carrying on the terminal canbon atom as a substituent an unsubstituted or monoor dimethyl-substituted seven-membered olefinically unsaturated bridged cycloaliphatic group containing a double bond in the u-position with respect to the said terminal carbon atom, or a substituted ethyl radical carrying on the terminal carbon atom as a substituent a 2- or 3-furyl, or 2- or 3-thienyl group, and wherein (d) two of the radicals represented by the symbols R R R and R can be linked to each other, except R to R to form a fiveor six-membered olefinically unsaturated cycloaliphatic ring which contains at most two double bonds and which can carry as substituents alkyl or alkenyl groups containing from 1 to 3 carbon atoms, or a sixmembered olefinically unsaturated bridged cycloaliphatic ring which contains one double bond and which can carry one or two methyl groups, or a furan or thiophene ring which can carry a methyl group, in order to form a carbonyl compound of formula R1 R6 R5 Ra R2 R1 R3 R4 III wherein the symbols R to R have the meaning defined above.

2. Process according to claim 1 which comprises using as a condensing agent at least one member selected from the group consisting of mineral and organic acids and their magnesium, aluminum, chromium, manganese, silver, cadmium, mercury, iron, cobalt, and palladium salts, and acidic salts.

3. Process according to claim 1 which comprises using as a condensing agent mercuric acetate, phosphoric acid or ammonium dihydrogen-phosphate.

4. Process according to claim 1 which comprises carrying out the condensation in the presence of an organic solvent selected from the group consisting of aromatic hydrocarbons, polyethylene glycol ethers and halogenated or nitrated aromatic hydrocarbons.

5. Process according to claim 1 which comprises using as a solvent an excess of one of the starting compounds.

I6. Process according to claim 1 which comprises carrying out the condensation in an inert atmosphere.

7. Process according to claim 1 which comprises repeating at least once the said condensation with as a starting allyl alcohol a compound resulting from the reduction of ,.carbonyl compound obtained by a preceding condensation in order to form a carbonyl compound of Formula III comprisingat least twoof the said building units.

8. Process according to claim 1 which comprises using as a substance capable of generating a butadienyl ether of Formula I under the condensation conditions a compound of formula R4 OY C(H)..== J: J(H)D-OH a R2 R1 OY IV which contains one double bond in one of the positions indicated by the dotted lines and in which one of the symbols n is zero and the other one is the figure 1 and Y, R R R and R have the same meaning as in Formula I.

9. Process according to claim 1 which comprises using as a substance capable of generating a butadienyl ether of Formula I under the condensation conditions a compound of formula wherein Y, R R R and R have the same meaning as in Formula I.

10. Process according to claim 1 which comprises using as a starting butadienyl ether a compound of Formula I wherein R is methyl and R R and R are hydrogen.

11. Process according to claim 1 which comprises using as a starting butadienyl ether a compound of Formula I wherein R R R and R are hydrogen.

12. Process according to claim 1 which comprises using as a starting allyl alcohol a compound of Formula II wherein R and R are hydrogen, R is methyl and R is a methyl, 2 (furyl-3)-ethyl, 2-methylene-4-pentenyl or 3-methyl-2,4-pentadienyl. 13. Process according to claim 1 which comprises using as a starting allyl alcohol a compound of Formula 11 wherein R5 and R are hydrogen and R and R are linked to each other, and together with their carrier carbon atoms, form a furan, thiophene or 7,7-dimethyl-3-bicycl0(3.1.1) heptene ring.

14. Process according to claim 1 which comprises using as a starting allyl alcohol a compound of Formula II wherein R and R are hydrogen, R is methyl and R is a 4-methyl-3-penteny1 radical.

15. Process according to claim 1 which comprises using as a starting allyl alcohol a compound of Formula II wherein R R and R, are hydrogen and R is'a 3-rnethyli- 3-pentenyl radical. l

16. Process according to claim 1 which comprisesusing as a starting allyl alcohol a compound of Formula 11 wherein R is hydrogen, R is methyl and R and R are linked to each other and, together with their carrier carbon atoms, form a 2-methyl-5-isopropyll-cyclohexene ring.

17. Process according to claim 1 which comprisesusing as a starting allyl alcohol a compound of Formula II wherein R is methyl, 'R is hydrogen and R and R are linked to each other and, together with their carrier carbon atoms, form a 2-methyl-5-isopropenyl-l-cyclohexene ring.

18. 5- (2-furyl)-2-pentenal. 19. 2-methyl-5-(2-furyl)-2-pentenal. 2-methyl-5 (2-furyl)-2-pentenol. 2-methyl-5 (2-fury1)-1-pentene. 2-methyl-5 (3-furyl)-2-pentenal. 2-methyl-5-(3-furyl)-2-pentenol. 2-methyl-4-(2-thenyl)-2-butenal.

References Cited UNITED STATES PATENTS 2,995,600 8/1961 Webb 260-488 HENRY R. JILES, Primary Examiner C. M. SHURKO, Assistant Examiner US. Cl. X.R.

CERlUflC/XYL O1" CQRRECTLON lnLcnt No. 3,054,399 I bntd April Inventor) Aux Fmxcls THOMAS I I l I 7 It is certified, Lhnt ginor appcars in the :xbbvc-identifidd paLc-nt and tha 'said- Letters-Patent are hereby corrected as shown below:

lines 35- 40 "6" should read Column 3 line 26 "terminal carbon a toms" should read "terminal carbon atom". v

Column 2 Colun m 3, line 3 5 "seven-members" should readv SQVeh-numbered- Column 3, lirie so "'x'z 1'1 1'1 R2 should read 0 c -cH'- (I: l: c CHO a R R8 v Column 6 line .34 "cu cu -fin om. should and i CH3- CH'(2-CH2-0H.

Co1 umn 9 line 51 "1os'-11-o'/1oo tort." should read: ms-110710 tqtr.

Column 10, line 2 "61(1001 'ss 90)" should read --6 9(100) s's( 90)--;

Co1umn 13, 1ine 66--T he angula should be indicated as "I" Sigried and sealad fibis Sth' day of December 1972.

(SEAL) Attsst:

ROBERT GQE'ISCHALJ Comm], saioner of Patents EDWARD M.FLETCEER ,J'R. Attestirxg Officgr 

